Agent API Reference

Relentless gives AI agents their own buildspace — the same product, a second room. Agents authenticate with a scoped API key, organize work using typed nodes, and share context with humans through a Fusion boundary.

curl https://www.relentless.build/api/nodes?depth=skeleton \
  -H "Authorization: Bearer rlnt_YOUR_KEY_HERE"

Authentication

All requests require a Bearer token in the Authorization header. Agent API keys start with rlnt_ and are scoped to a single buildspace.

curl https://www.relentless.build/api/nodes \
  -H "Authorization: Bearer rlnt_4bc36fc7aa00c62d2ee0e0185b9658293bd769b4"

Nodes

Nodes are the core data primitive. Every piece of content is a node with a kind, title, and content (kind-specific JSON).

// Skeleton response
{
  "nodes": [
    {
      "id": "019c7389-d819-...",
      "kind": "nodebook",
      "title": "Home",
      "pinned": false,
      "archived": false,
      "systemKey": "home",
      "createdAt": "2026-02-19T01:35:39Z",
      "updatedAt": "2026-02-19T01:35:39Z",
      "_parentIds": []
    }
  ]
}

curl -X POST https://www.relentless.build/api/nodes \
  -H "Authorization: Bearer rlnt_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "kind": "notebook",
    "title": "Research Notes",
    "content": { "body": "Initial findings..." },
    "parentId": "home-node-id"
  }'

// 201 Created
{
  "id": "019c738b-9b9f-...",
  "kind": "notebook",
  "title": "Research Notes",
  "content": { "body": "Initial findings..." },
  "shared": false,
  "meta": {
    "contentLength": 28,
    "maxContentLength": 50000,
    "remainingCapacity": 49972
  }
}

curl -X PATCH https://www.relentless.build/api/nodes/NODE_ID \
  -H "Authorization: Bearer rlnt_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "shared": true, "title": "Updated Title" }'

Node Kinds

Each node kind has a specific content schema. Here are the available kinds and their content shapes.

// notebook
{ body?: TipTapJSON | string }

// bookmark
{
  url: string;
  description?: string;
  favicon?: string;
}

// project
{
  status: "active" | "paused" | "done" | "archived";
  description?: string;
  tags?: string[];
}

// task (done is REQUIRED)
{
  done: boolean;
  dueAt?: string;       // ISO date
  priority?: 1 | 2 | 3; // 1=high, 2=medium, 3=low
  notes?: string;
}

// decision (all four REQUIRED)
{
  what: string;
  why: string;
  purpose: string;
  constraints: string;
}

// code
{
  language: string;
  source: string;
}

// snippet
{
  text: string;
  description?: string;
}

// event
{
  startsAt: string;
  endsAt?: string;
  location?: string;
}

// tasklist
{
  items: [{
    id: string;
    value: string;
    done?: boolean;
    priority?: 1 | 2 | 3;
    order: number;
    createdAt: string;
  }];
}

// contact
{
  type: "person" | "organization" | "ai";
  email?: string;
  phone?: string;
  company?: string;
}

Edges

Edges connect nodes. Four kinds of relationships are supported.

[{
  "edge": {
    "id": "...",
    "sourceId": "...",
    "targetId": "...",
    "kind": "contains"
  },
  "sourceNode": {
    "id": "...",
    "title": "Home",
    "kind": "nodebook"
  },
  "targetNode": {
    "id": "...",
    "title": "My Notes",
    "kind": "notebook"
  }
}]

curl -X POST https://www.relentless.build/api/edges \
  -H "Authorization: Bearer rlnt_YOUR_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "sourceId": "parent-node-id",
    "targetId": "child-node-id",
    "kind": "contains"
  }'

Fusion — The Collaboration Boundary

The Fusion Node bridges the agent buildspace and the human buildspace. Shared nodes appear here automatically — no events, no webhooks. The query is the sync.

// Fusion query response
{
  "nodes": [
    {
      "id": "...",
      "title": "Agent's Research",
      "_source": "self"
    },
    {
      "id": "...",
      "title": "Human's Brief",
      "_source": "linked"
    }
  ]
}

System Nodes

System nodes are auto-created nodes with special keys. Retrieve them by key name instead of ID.

Returns the full node object. Creates the system node if it doesn't exist yet. Known keys: home, fusion, video-history.

Buildspaces

List buildspaces accessible to the authenticated key. Agent keys see their scoped buildspace and the linked human buildspace. Response includes buildspace limits.

{
  "buildspaces": [{
    "id": "...",
    "name": "My Agent Space",
    "type": "agent",
    "role": "owner",
    "memberCount": 1,
    "linkedBuildspaceId": "...",
    "linkedBuildspaceName": "Personal"
  }],
  "limits": {
    "personal": { "max": 1, "current": 1, "remaining": 0 },
    "team": { "max": 3, "current": 0, "remaining": 3 },
    "agent": { "max": 2, "current": 1, "remaining": 1 }
  }
}

Rate Limits

Agent API keys are rate-limited per key. Human sessions are exempt.

Additional limits

// 429 Too Many Requests
{
  "error": "rate_limit_exceeded",
  "message": "You've used 50 of your 50 node creates for this hour. The limit resets at 14:00 UTC (12 minutes from now).",
  "limit": 50,
  "remaining": 0,
  "resetAt": "2026-02-05T14:00:00Z",
  "retryAfterSeconds": 720
}

// 413 Content Too Large
{
  "error": "content_too_large",
  "message": "Content exceeds maximum size of 50000 characters (current: 50012, overage: 12)",
  "size": 50012,
  "maxSize": 50000
}

Errors

All errors follow a consistent shape. The message field is always human-readable.

{ error: string; message?: string; details?: unknown }

Security

Every layer of the Agent API is designed to prevent abuse and protect data isolation.